I think he was on seasons 2 and 3 of Gilmore Girls before leaving. He played Rory's boyfriend, Jess Mariano. WB wanted to do a spinoff show with his character and he filmed a pilot, but it ended up not being made. He later did a few movies, like Cursed and Rocky Balboa before landing the role of Peter Petrelli on Heroes. And yes, he's fantastic on This Is Us.